The present application relates generally to methods and apparatuses for die casting, and more specifically to die casting plunger tips and methods used for casting high temperature alloy components.
Die casting is a metal casting process, which involves injecting a molten metal into a mold or multi-part die to form a component. The die casting process is commonly used for the manufacture of various metal components. A number of die casting apparatuses, generally tailored to low temperature metal solutions such as aluminum, zinc, and magnesium, are known in the art. These die casting apparatuses use a plunger or piston to force molten metal through a shot tube into a mold. A tip of the plunger serves to force the molten metal into the mold, while also forming a seal within the shot tube to prevent backflow of the molten metal around the plunger. Forming a seal necessitates that a gap between the plunger tip and the shot tube be controlled to a very small clearance. Because a high heat load associated with the molten metal can cause thermal expansion of the plunger tip and shot tube, a coolant is supplied to the plunger tip to limit thermal expansion of the plunger tip and limit radial binding of the plunger tip within the shot tube. The plunger tip is typically water cooled with water being supplied to a backside of the tip and evacuated through an annular jacket. Various configurations are tailored to low temperature melt solutions (e.g., generally around or below 1500° F. (815° C.)) and are not effective for managing higher heat loads such as exist in the casting of superalloys, which generally involve temperatures above 2500° F. (1371° C.). In addition to providing ineffective thermal management for high heat loads, high thermal stresses may limit long-term durability of the plunger tips, and thus these configurations may not work for the casting of superalloys.
A plunger tip or plunger tip assembly is needed for die casting of superalloy components, which can allow for improved thermal management, including better control of radial deflection (expansion and contraction) of a tip under high transient thermal load, and which can extend long-term durability of the plunger tip.